Light generator including debris shielding assembly, photolithographic apparatus including the light generator

ABSTRACT

A method of manufacturing an integrated circuit (IC) device includes forming a photoresist layer on a substrate, and exposing the photoresist layer to light by using a photolithographic apparatus including a light generator. The light generator includes a chamber having a plasma generation space, an optical element in the chamber, and a debris shielding assembly between the optical element and the plasma generation space in the chamber, and the debris shielding assembly includes a protective film facing the optical element and being spaced apart from the optical element with a protective space therebetween, the protective space including an optical path, and a protective frame to support the protective film and to shield the protective space from the plasma generation space.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. patent application Ser. No. 16/234,929filed Dec. 28, 2018, which is incorporated by reference herein in itsentirety.

Korean Patent Application No. 10-2018-0056689, filed on May 17, 2018, inthe Korean Intellectual Property Office, and entitled: “Light generatorincluding debris shielding assembly, photolithographic apparatusincluding the light generator, and method of manufacturing integratedcircuit device using the photolithographic apparatus,” is incorporatedby reference herein in its entirety.

BACKGROUND 1. Field

The present disclosure relates to a light generator, a photolithographicapparatus including the same, and a method of manufacturing anintegrated circuit (IC) device by using the apparatus, and moreparticularly, to a light generator providing extreme ultraviolet (EUV)light, a photolithographic apparatus including the light generator, anda method of manufacturing an IC device by using the apparatus.

2. Description of the Related Art

Recently, in accordance with high integration of semiconductor devices,various photolithography techniques for forming fine patterns have beendeveloped. In particular, as the degree of integration of semiconductordevices increases, the critical dimension (CD) of a photoresist patternis further decreasing. To form such a photoresist pattern having a fineCD, EUV light may be adopted as a light source of a photolithographicapparatus. To generate EUV light in the photolithographic apparatus,laser light may be radiated onto a target material in a vacuum chamberto convert the target material into a plasma state.

SUMMARY

According to an aspect of the present disclosure, there is provided amethod of manufacturing an integrated circuit (IC) device, the methodincluding forming a photoresist layer on a substrate, and exposing thephotoresist layer to light by using a photolithographic apparatusincluding a light generator, wherein the light generator includes achamber having a plasma generation space, an optical element in thechamber, and a debris shielding assembly between the optical element andthe plasma generation space in the chamber, wherein the debris shieldingassembly includes a protective film facing the optical element and beingspaced apart from the optical element with a protective spacetherebetween, the protective space including an optical path, and aprotective frame to support the protective film and to shield theprotective space from the plasma generation space.

According to another aspect of the present disclosure, there is provideda method of manufacturing an integrated circuit (IC) device, the methodincluding forming a photoresist layer on a substrate, and exposing thephotoresist layer to light by using a photolithographic apparatusincluding a light generator, wherein the light generator includes achamber having a plasma generation space, an optical collector in thechamber, the optical collector having a reflective surface, and a debrisshielding assembly between the optical collector and the plasmageneration space in the chamber, wherein the debris shielding assemblyincludes a protective film being spaced apart from the reflectivesurface with a protective space therebetween and facing the reflectivesurface, the protective space including an optical path, and aprotective frame that is in contact with an edge portion of the opticalcollector and supports the protective film.

According to yet another aspect of the present disclosure, there isprovided a method of manufacturing an integrated circuit (IC) device,the method including forming a photoresist layer on a substrate, andexposing the photoresist layer to light by using a photolithographicapparatus including a light generator, wherein the light generatorincludes a chamber having a plasma generation space, an opticalcollector in the chamber, the optical collector having a reflectivesurface, and a debris shielding assembly between the optical collectorand the plasma generation space in the chamber, wherein the debrisshielding assembly includes a protective film facing the reflectivesurface with a protective space therebetween, the protective spaceincluding an optical path, the protective film having a through holeformed in a position corresponding to the optical path in the protectivefilm.

BRIEF DESCRIPTION OF THE DRAWINGS

Features will become apparent to those of skill in the art by describingin detail exemplary embodiments with reference to the attached drawings,in which:

FIG. 1 illustrates a schematic view of main elements in a lightgenerator according to embodiments of the present disclosure;

FIG. 2A illustrates a plane view of an example configuration of a debrisshielding assembly according to an embodiment;

FIG. 2B illustrates a cross-sectional view taken along line B-B′ in FIG.2A;

FIG. 2C illustrates a plane view of a protective film included in thedebris shielding assembly in FIGS. 2A and 2B;

FIG. 2D illustrates a plane view of an outer fixing portion included inthe debris shielding assembly in FIGS. 2A and 2B;

FIG. 2E illustrates a plane view of a first buffer film included in thedebris shielding assembly in FIGS. 2A and 2B;

FIG. 2F illustrates a state before the debris shielding assembly ofFIGS. 2A and 2B and an optical collector are coupled together;

FIG. 2G illustrates a state where the debris shielding assembly of FIGS.2A and 2B and the optical collector are coupled together.

FIG. 3A illustrates a plane view of a debris shielding assemblyaccording to another embodiment;

FIG. 3B illustrates a cross-sectional view taken along line B-B′ in FIG.3A;

FIG. 3C illustrates a state in which the debris shielding assembly ofFIGS. 3A and 3B and the optical collector are coupled together;

FIG. 4A illustrates a plane view of a debris shielding assemblyaccording to another embodiment;

FIG. 4B illustrates a cross-sectional view taken along line B-B′ in FIG.4A;

FIG. 5A illustrates a plane view of a debris shielding assemblyaccording to another embodiment;

FIG. 5B illustrates a cross-sectional view taken along line B-B′ in FIG.5A;

FIG. 5C illustrates a state where the optical collector and the debrisshielding assembly are coupled together;

FIG. 6A illustrates a cross-sectional view of a debris shieldingassembly according to another embodiment;

FIG. 6B illustrates a state where the optical collector and the debrisshielding assembly are coupled together;

FIG. 6C illustrates an enlarged view of a region “CX1” in FIG. 6B;

FIG. 7A illustrates a cross-sectional view of a debris shieldingassembly according to another embodiment;

FIG. 7B illustrates a state where the optical collector and the debrisshielding assembly are coupled together;

FIG. 7C illustrates an enlarged view of a region “CX2” in FIG. 7B;

FIG. 7D illustrates an enlarged partial cross-sectional view of a shieldportion in a protective frame of the debris shielding assembly of FIG.7A;

FIG. 8 illustrates a cross-sectional view of a debris shielding assemblyaccording to another embodiment;

FIG. 9 illustrates a cross-sectional view of a debris shielding assemblyaccording to another embodiment;

FIG. 10 illustrates a schematic view of main elements of aphotolithographic apparatus according to embodiments of the presentdisclosure;

FIG. 11 illustrates a flowchart of a method of manufacturing anintegrated circuit (IC) device, according to embodiments of the presentdisclosure; and

FIG. 12 illustrates a block diagram of a memory system including an ICdevice manufactured by using the method of manufacturing an IC device,according to embodiments of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 is a schematic view illustrating main elements of a lightgenerator 100 according to embodiments of the present disclosure.

Referring to FIG. 1 , the light generator 100 may be an extremeultraviolet (EUV) light generator which generates EUV light using alaser produced plasma (LPP) method. The light generator 100 may includea chamber 110 having a plasma generation space (PS), optical elementsarranged in the chamber 110, and a laser focusing system 160 whichradiates a laser beam into the chamber 110. The optical elements mayinclude an optical collector 120 and a spectral purity filter (SPF) 130.However, the optical elements are not limited thereto.

The chamber 110 may be provided with an introduction window 112 throughwhich a laser beam (LB) radiated from the laser focusing system 160 maybe introduced into the chamber 110. The chamber 110 may be maintained ata vacuum state by an evacuation apparatus 140, e.g., a vacuum pump,installed in the chamber 110.

The light generator 100 may include a droplet generator 152 whichprovides droplets (DL) of a target material into the chamber 110, and acatcher 154 which collects droplets not involved in a plasma generationreaction among the droplets provided from the droplet generator 152. Inthe chamber 110, the droplets (DL) may flow in a straight line directionfrom the droplet generator 152 toward the catcher 154. The targetmaterial may include Sn, Li, Ti, Xe, or a combination thereof. In someembodiments, the target material may include pure tin (Sn), a Sncompound, a Sn alloy, or a combination thereof. The Sn compound may beat least one of, e.g., SnBr₄, SnBr₂, and SnH. The Sn alloy may be atleast one of, e.g., Sn—Ga alloy, a Sn—In alloy, and a Sn—In—Ga alloy.However, embodiments are not limited thereto.

The laser focusing system 160 may radiate the laser beam (LB) onto thedroplets (DL) of the target material to thereby convert the droplets ofthe target material into a plasma state in the plasma generation space(PS). For example, the laser focusing system 160 may radiate a pre-pulselaser beam onto a primary target, i.e., the droplet (DL) of the targetmaterial, to generate a secondary target, and radiate a main pulse laserbeam onto the secondary target to thereby generate plasma from thedroplets (DL) of the target material. The pre-pulse laser beam may be abeam having a wavelength of about 1064 nm provided from a Nd:YAG(Yttrium Aluminum Garnet) laser device. The main pulse laser beam may bea beam having a wavelength of about 10.6 m provided from a CO₂ laserdevice. However, types of the pre-pulse laser beam and the main pulselaser beam are not limited to the above examples. The laser beam (LB)generated from the laser focusing system 160 may be focused onto thedroplet (DL) in the chamber 110 through the introduction window 112.While plasma is generated from the droplet (DL), the chamber 110 may bemaintained in a comparatively high vacuum condition of about 1 Torr orless.

The optical collector 120 may have a reflective surface 122 capable ofcollecting and reflecting EUV light having a wavelength of about 1 nm toabout 31 nm, e.g., about 13.5 nm, from light having various wavelengthsemitted from the plasma generated from the droplets (DL) of the targetmaterial in the chamber 110. For example, as illustrated in FIG. 1 , theoptical collector 120 may be positioned in the chamber 110, such thatthe reflective surface 122 of the optical collector 120 may face theplasma generation space (PS). The reflective surface 122 may be aconcave surface. The reflective surface 122 may selectively reflect EUVlight having a wavelength of about 13.5 nm. The optical collector 120may include a multilayer mirror providing the reflective surface 122.The multilayer mirror may be configured as a stack structure in which aplurality of layers, e.g., a Mo layer, a Si layer, a SiC layer, a B₄Clayer, a Mo₂C layer, and a Si₃N₄ layer, are alternately stacked upon oneanother. The optical collector 120 may have an aperture (AP) in asubstantially central portion of the optical collector 120, and theaperture (AP) penetrates through the reflective surface 122. Thereflective surface 122 may be a curved surface having a prolateellipsoidal shape concavely converging to the aperture (AP). The laserbeam (LB) provided from the laser focusing system 160 may be irradiatedthrough the introduction window 112 of the chamber 110 and through theaperture (AP) of the optical collector 120 onto the droplets (DL) of thetarget material to generate plasma in the plasma generation space (PS).

The EUV light (LT) collected from the plasma generated in the chamber110 may be provided to an exposure apparatus, e.g., a scanner or astepper, through the SPF 130. For example, as illustrated in FIG. 1 ,light of the EUV light (LT) collected from the plasma generated in thechamber 110 is reflected from the reflective surface 122 of the opticalcollector 120 toward the SPF 130, e.g., the SPF 130 and the introductionwindow 112 may be on opposite sidewalls of the chamber 110. The SPF 130may remove unnecessary light of the EUV light (LT) collected from theplasma generated in the chamber 110, i.e., UV rays, visible rays, andinfrared rays, having a longer wavelength than the EUV light (LT) andmay transmit only desired EUV light, e.g., light having a wavelength ofabout 13.5 nm, to the exposure apparatus.

The light generator 100 may further include a debris shielding assembly170 arranged between the optical collector 120 and the plasma generationspace (PS) in the chamber 110. The debris shielding assembly 170 mayinclude a protective film 172, a protective frame 174 supporting theprotective film 172, and a fixing member 176 for fixing the protectivefilm 172 to the protective frame 174.

In detail, referring to FIG. 1 , the protective film 172 may cover,e.g., overlap, the reflective surface 122 of the optical collector 120.The protective film 172 may be arranged at a location separated from theoptical collector 120 with a protective space 180 between the protectivefilm 172 and the reflective surface 122 of the optical collector 120, soa path of the EUV light (LT) is through the protective space 180. Forexample, as illustrated in FIG. 1 , the protective film 172 may bespaced apart a predetermined distance from the reflective surface 122 ofthe optical collector 120, so the protective space 180 may separatebetween the protective film 172 and the reflective surface 122. Forexample, as illustrated in FIG. 1 , since the reflective surface 122 maybe a curved surface, and the protective film 172 may have a flat surfacefacing the reflective surface 122, the distance between the reflectivesurface 122 and the surface of the protective film 172 facing thereflective surface 122 may be non-constant.

The protective film 172 may have a through hole 172LH in a substantiallycentral portion of the protective film 172, e.g., the through hole 172LHmay be aligned with the aperture (AP) of the optical collector 120.Therefore, the laser beam (LB) radiated from the laser focusing system160 may be irradiated onto the droplet (DL) of the target materialthrough the through hole 172LH of the protective film 172 after passingthrough the introduction window 112 of the chamber 110 and through theaperture (AP) of the optical collector 120. In some embodiments, theprotective film 172 may not have the through hole 172LH.

The protective frame 174 may be arranged to contact an edge portion ofthe optical collector 120, e.g., the protective frame 174 may connectbetween the edge portion of the optical collector 120 and the protectivefilm 172. The protective frame 174 may shield, at the edge portions ofthe protective film 172 and the optical collector 120, the protectivespace 180 from the plasma generation space (PS). For example, asillustrated in FIG. 1 , the protective frame 174 may be directly betweenthe edge portion of the optical collector 120 and the protective film172, e.g., along entire perimeters of the optical collector 120 and theprotective film 172, so the protective space 180 may be shielded, e.g.,completely separated from the plasma generation space (PS), e.g., withthe exception of the through hole 172LH.

The protective frame 174 may have a planar shape corresponding to aplanar shape of the edge portion of the optical collector 120. Forexample, when the edge portion of the optical collector 120 has acircular ring shape in a front view facing the reflective surface 122 ofthe optical collector 120, e.g., when looking from the SPF 130 towardthe reflective surface 122, the protective frame 174 may have a circularring shape corresponding to, e.g., overlapping, the edge portion of theoptical collector 120. For example, the protective frame 174 may, e.g.,continuously, extend along an, e.g., entire, edge perimeter of theoptical collector 120.

In some embodiments, the protective film 172 may include a material thatis transparent to the EUV light (LT). In some other embodiments, theprotective film 172 may include a material transparent to the laser beam(LB) radiated from the laser focusing system 160 and the EUV light (LT).For example, the protective film 172 may include a material transparentto a laser beam having a wavelength of about 1064 nm, a laser beamhaving a wavelength of about 10.6 m, and EUV light having a wavelengthof about 13.5 nm. In this case, even when the protective film 172 doesnot have the through hole 172LH, the laser beam (LB) radiated from thelaser focusing system 160 may transmit through the protective film 172.

In some embodiments, the protective film 172 may include at least one ofcarbon isomers. For example, the protective film 172 may include carbonnanotubes, diamond, graphite, graphene, fullerene, or a combinationthereof.

In some embodiments, the protective film 172 may include a carbonnanotube film including single-wall carbon nanotubes (SWCNT), multiwallcarbon nanotubes (MWCNT), or a combination thereof.

In some other embodiments, the protective film 172 may include a diamondlayer. In some embodiments, the diamond layer may be a layer formed byusing a chemical vapor deposition (CVD) process. For example, thediamond layer may be obtained by depositing diamond on a supportsubstrate with a combination of methane and hydrogen gases at atemperature of about 800° C. to about 1,200° C. under reduced pressure.The inclusion of the hydrogen gas may prevent growth of graphite duringnucleation and growth of the diamond. However, according to embodimentsof the present disclosure, a process of forming the diamond layeravailable as the protective film 172 is not limited to theabove-described example method. A diamond layer available as theprotective film 172 may be obtained through any of a variety of methodsknown in the art.

In some other embodiments, the protective film 172 may include adiamond-like carbon (DLC) film. The DLC film may include amorphouscarbon including a sp³ carbon bond and a sp² carbon bond. The DLC filmmay include sp³ carbon bonds and sp² carbon bonds in a ratio of about1:1. However, embodiments are not limited thereto.

In some other embodiments, the protective film 172 may include agraphene-carbon nanotube composite. The graphene-carbon nanotubecomposite may include graphene and carbon nanotubes in a weight ratio ofabout 2:1 to about 1:5.

In some embodiments, the protective film 172 may have a thickness ofabout 2 nm to about 500 nm. However, embodiments of the presentdisclosure are not limited thereto.

The protective frame 174 of the debris shielding assembly 170 maysupport the protective film 172, in contact with the edge portion of theoptical collector 120. The protective frame 174 may include a metal. Forexample, the protective frame 174 may include Al, stainless steel, Mo,or a combination thereof.

The debris shielding assembly 170 may include the fixing member 176 forfixing the protective film 172 to the protective frame 174. In someembodiments, the fixing member 176 may include an adhesive layer. Insome embodiments, the adhesive layer may include a thermosetting epoxyresin or bovine serum albumin (BSA). However, embodiments of the presentdisclosure are not limited thereto.

In some embodiments, the debris shielding assembly 170 may not includethe fixing member 176 between the protective film 172 and the protectiveframe 174. Instead, the protective film 172 may be fixed directly ontothe protective frame 174 by pressing.

Although FIG. 1 illustrates an embodiment in which the optical collector120 as an optical element is protected by the debris shielding assembly170, embodiments of the present disclosure are not limited to theembodiment illustrated in FIG. 1 . For example, the debris shieldingassembly 170 may be installed to protect the SPF 130, e.g., between theSPF 130 and the plasma generation space (PS), or other optical elementsin the chamber 110.

For example, if the debris shielding assembly 170 were not in thechamber 110, during plasma generation in the plasma generation space PS,debris, e.g., particles unable to become plasma, would be deposited onsurfaces of optical elements, e.g., on a surface of the opticalcollector 120 or on a surface of the SPF 130, thereby lowering operationefficiency, e.g., reflectance or transmittance, thereof. While effortscould be made to clean the surfaces of the optical elements in thechamber 110, e.g., via various cleaning gases or radicals obtained fromcleaning gases, the cleaning processes, e.g., using cleaning gases orradicals, would raise the processing costs, and optical characteristics,e.g., reflectance, of the optical elements would be deteriorated due torepeated deposition of debris generated from the target material in thechamber 110. Further, the surfaces of the optical elements would also bedeteriorated by the cleaning gases or radicals, and accordingly,durability would be lowered.

In contrast, according to embodiments of the present disclosure, thelight generator 100 may include the debris shielding assembly 170installed between optical elements which are prone to contamination bydebris and the plasma generation space (PS) in the chamber 110. Forexample, as illustrated in FIG. 1 , the debris shielding assembly 170may be installed between the optical collector 120 and the plasmageneration space (PS). Accordingly, when debris generated from thedroplet (DL) in the plasma generation space (PS) flows from the plasmageneration space (PS) toward the reflective surface 122 of the opticalcollector 120, various travel paths of the debris to the reflectivesurface 122 of the optical collector 120 may be blocked by theprotective film 172 and the protective frame 174. In particular, evenwhen the debris generated from the droplet (DL) in the plasma generationspace (PS) is likely to move from the plasma generation space (PS)towards the reflective surface 122 of the optical collector 120 throughthe space between the protective film 172 and the optical collector 120via various travel paths of the debris, there is no concern of flowingof the debris from the plasma generation space (PS) towards thereflective surface 122 of the optical collector 120 through the spacebetween the protective film 172 and the optical collector 120, since theprotective space 180 is shielded by the protective frame 174 of thedebris shielding assembly 170 at the edge portions of the protectivefilm 172 and the optical collector 120.

Thus, it is unlikely that debris generated in the plasma generationspace (PS) flows to the reflective surface 122 of the optical collector120 and into the protective space 180 extending a predetermined distancefrom the reflective surface 122 of the optical collector 120 to theprotective film 172. Accordingly, the reflective surface 122 of theoptical collector 120 may be protected from contamination by the debris,and the performance of the optical collector 120 may also be maintainedwithout periodic cleaning.

In the light generator 100 according to the one or more embodiments ofthe present disclosure, the internal environment of the chamber 110 maybe maintained under a stable operation condition only by periodiccleaning and/or replacement of the protective film 172 and theprotective frame 174, without cleaning the optical elements in thechamber 110. Accordingly, without the need to perform the cleaningprocess using a gas source, which may increase the process cost anddeteriorate the optical elements, the contamination of the opticalelements by debris and consequential productivity reduction may beprevented or substantially minimized.

FIG. 2A is a plane view illustrating an example configuration of adebris shielding assembly 270A which may be employed in a lightgenerator according to embodiments of the present disclosure. FIG. 2B isa cross-sectional view taken along line B-B′ in FIG. 2A. In FIGS. 2A and2B, like reference numerals as those in FIG. 1 refer to like elements,and thus redundant descriptions thereof are omitted here.

Referring to FIGS. 2A and 2B, similar to the debris shielding assembly170 illustrated in FIG. 1 , the debris shielding assembly 270A mayinclude a protective film 272A and a protective frame 274 supporting theprotective film 272A.

The protective film 272A may have a substantially same configuration asthat of the protective film 172 described above with reference to FIG. 1. The protective film 272A may have a through hole 272LH in asubstantially central portion thereof.

The protective frame 274 may include a support portion 274A, a shieldportion 274B that is integrally connected with the support portion 274Aand extends between the support portion 274A and the protective film272A, and an outer fixing portion 274C that faces the shield portion274B with the protective film 272A therebetween. The outer fixingportion 274C supports the protective film 272A in cooperation with theshield portion 274B.

The support portion 274A, the shield portion 274B, and the outer fixingportion 274C, which constitute the protective frame 274, may have asubstantially circular planar shape. Outer diameters of the supportportion 274A, the shield portion 274B, and the outer fixing portion 274Cmay substantially be the same. The support portion 274A, the shieldportion 274B, and the outer fixing portion 274C may include a metal. Forexample, the support portion 274A, the shield portion 274B, and theouter fixing portion 274C may include Al, stainless steel, Mo, or acombination thereof.

The support portion 274A may be a ring member having a straightcross-sectional shape extending from the shield portion 274B. A width WAof the support portion 274A may be less than a width WB of the shieldportion 274B. In some embodiments, the width WB of the shield portion274B may substantially be the same as the width WC of the outer fixingportion 274C. In some other embodiments, the width WB of the shieldportion 274B may be different from the width WC of the outer fixingportion 274C.

The protective frame 274 may further include a first buffer film 278Abetween the shield portion 274B and the protective film 272A, and asecond buffer film 278B between the protective film 272A and the outerfixing portion 274C. In some embodiments, the first buffer film 278A andthe second buffer film 278B may include an elastic material. Forexample, each of the first buffer film 278A and the second buffer film278B may include a polyimide film and/or an engineering plasticmaterial, e.g., polyetheretherketone (PEEK).

The protective frame 274 may further include a fixing member 292 formaintaining the protective film 272A and the protective frame 274 boundto each other. The fixing member 292 may include a screw. In someembodiments, the fixing member 292 may include a metal. However,embodiments of the present disclosure are not limited thereto.

FIG. 2C is a plane view of the protective film 272A included in thedebris shielding assembly 270A as illustrated in FIGS. 2A and 2B.

Referring to FIG. 2C, the protective film 272A may have a circular shapein a plane view, having a substantially same outer diameter as thediameter of the protective frame 274, e.g., the protective film 272A mayhave a same outer diameter as an outer diameter of the ring-shapedprotective frame 274. The protective film 272A may include a throughhole 272LH in a substantially central portion thereof and a plurality ofholes 272H in, e.g., spaced apart along, an edge portion thereof. Thefixing member 292 illustrated in FIGS. 2A and 2B may penetrate throughthe plurality of holes 272H. A material of the protective film 272A maybe the same as that of the protective film 172 described above withreference to FIG. 1 .

FIG. 2D is a plane view of the outer fixing portion 274C included in thedebris shielding assembly 270A as illustrated in FIGS. 2A and 2B.

Referring to FIG. 2D, the outer fixing portion 274C may have a circularshape in a plane view. The outer fixing portion 274C may include aplurality of holes 274H which the fixing member 292 illustrated in FIGS.2A and 2B may penetrate through. A planar structure of the shieldportion 274B illustrate in FIGS. 2A and 2B may substantially be the sameas the planar structure of the outer fixing portion 274C illustrated inFIG. 2D.

FIG. 2E is a plane view of the first buffer film 278A included in thedebris shielding assembly 270A as illustrated in FIGS. 2A and 2B.

Referring to FIG. 2E, the first buffer film 278A may have a circularplanar shape. The first buffer film 278A may include a plurality ofholes 278H which the fixing member 292 illustrated in FIGS. 2A and 2Bpenetrates through. A planar structure of the second buffer film 278Billustrated in FIGS. 2A and 2B may substantially be the same as theplanar structure of the first buffer film 278A illustrated in FIG. 2E.

FIG. 2F illustrates a state before the debris shielding assembly 270Aand the optical collector 120 are coupled together. FIG. 2G illustratesa state where the debris shielding assembly 270A and the opticalcollector 120 are coupled together.

Referring to FIG. 2F, in the debris shielding assembly 270A, an innerdiameter AD1 of the support portion 274A may be greater than an innerdiameter BD1 of the shield portion 274B. An outer diameter OD of theoutermost edge portion of the optical collector 120 farthest away fromthe aperture AP may be equal to or less than the inner diameter AD1 ofthe support portion 274A. An inner diameter ID of the edge portion ofthe optical collector 120 may substantially be the same as an innerdiameter BD1 of the shield portion 274B.

Therefore, to couple the optical collector 120 to the debris shieldingassembly 270A, the edge portion of the optical collector 120 may beinserted into the support portion 274A. That is, the edge portion of theoptical collector 120 may be positioned to abut, e.g., directly contact,a surface of the shield portion 274B facing the optical collector 120,so the support portion 274A is flush against and surrounds an outerdiameter of the optical collector 120. As a result, as illustrated inFIG. 2G, the edge portion of the optical collector 120 may partially besurrounded by the support portion 274A.

In some embodiments, in the light generator 100 (see FIG. 1 ), theoptical collector 120 may be installed such that the reflective surface122 is inclined in a vertical direction (Z direction) with respect to ahorizontal direction (X-Y plane direction) at a certain angle, e.g., bya first acute angle (a). The laser beam (LB) may be radiated from thelaser focusing system 160 at a certain tilt angle, e.g., the first acuteangle (a), in a vertical direction (Z direction) with respect to thehorizontal direction (X-Y plane direction, such as to pass through theaperture (AP) of the optical collector 120 and the through hole 272LH ofthe protective film 272A.

As illustrated in FIG. 2G, with the optical collector 120 coupled to thedebris shielding assembly 270A, the protective film 272A facing thereflective surface 122 of the optical collector 120 may extend tilted ata predetermined angle towards the optical collector 120, e.g., at asecond acute angle 3, with respect to the vertical direction (Zdirection). To couple the optical collector 120 to the debris shieldingassembly 270A, as the edge portion of the optical collector 120 isinserted into the support portion 274A, an upper portion of the supportportion 274A and an upper portion of the shield portion 274B of thedebris shielding assembly 270A may contact the upper edge portion of theoptical collector 120 due to gravity, so that the upper edge portion ofthe optical collector 120 may support the debris shielding assembly270A. Accordingly, no binding tools may be needed for coupling theoptical collector 120 to the debris shielding assembly 270A.

The shield portion 274B may have an inner surface S1 facing theprotective space 180 between the support portion 274A and the protectivefilm 272A. In the state where the optical collector 120 and the debrisshielding assembly 270A are coupled together, an edge of the innersurface S1 of the shield portion 274B and an edge portion of thereflective surface 122 of the optical collector 120 may contact eachother, and the inner surface S1 and the reflective surface 122 maysmoothly extend, e.g., may be level with each other and directly contacteach other, forming one, e.g., sealed, plane without a step differencein a contact region between the inner surface S1 and the reflectivesurface 122.

In the light generator 100 illustrated in FIG. 1 , the debris shieldingassembly 270A illustrated in FIGS. 2A and 2B may be employed instead ofthe debris shielding assembly 170. In the state where the opticalcollector 120 and the debris shielding assembly 270A are coupledtogether, the protective film 272A and the shield portion 274B mayshield the protective space 180 from the plasma generation space (PS)(see FIG. 1 ). Accordingly, the debris generated in the plasmageneration space (PS) may unlikely flow into the protective space 180between the reflective surface 122 and the protective film 272A from theplasma generation space (PS). In particular, due to the shield portion274B between the edge portion of the optical collector 120 and theprotective film 272A, the debris generated in the plasma generationspace (PS) may unlikely flow through a gap between the edge portion ofthe optical collector 120 and the protective film 272A into theprotective space 180 and the reflective surface 122 of the opticalcollector 120 from the plasma generation space PS. Accordingly, thereflective surface 122 of the optical collector 120 may be protectedfrom contamination by the debris.

FIG. 3A is a plane view for explaining an example configuration of adebris shielding assembly 270B according to an embodiment, which may beused in the light generator according to embodiments of the presentdisclosure. FIG. 3B is a cross-sectional view taken along line B-B′ inFIG. 3A. FIG. 3C is a view illustrating a state in which the debrisshielding assembly 270B and the optical collector 120 are coupled. InFIGS. 3A to 3C, like reference numerals as those in FIGS. 1 to 2G referto like elements, and thus redundant descriptions thereof are omitted.

Referring to FIGS. 3A to 3C, the debris shielding assembly 270B may havea substantially same structure as the debris shielding assembly 270Aillustrated in FIGS. 2A and 2B. Unlike the debris shielding assembly270A, the debris shielding assembly 270B may not have the through hole272LH (see FIGS. 2A to 2C) at a center portion. Accordingly, the laserbeam (LB) passing through the aperture (AP) of the optical collector 120after being radiated from the laser focusing system 160 may betransmitted through a protective film 272B to irradiate the droplet (DL)of the target material (see FIG. 1 ). Examples of the material of theprotective film 272B may be the same as those of the protective film 172described above with reference to FIG. 1 . The debris shielding assembly270B illustrated in FIGS. 3A and 3B may be employed in the lightgenerator 100 of FIG. 1 , instead of the debris shielding assembly 170.

In the state where the optical collector 120 and the debris shieldingassembly 270B are coupled together, the protective film 272B and theshield portion 274B may shield the protective space 180 from the plasmageneration space (PS)(see FIG. 1 ). Accordingly, the debris generated inthe plasma generation space (PS) is unlikely to flow through a gapbetween the edge portion of the optical collector 120 and the protectivefilm 272B into the protective space 180 and the reflective surface 122of the optical collector 120 from the plasma generation space (PS).Accordingly, the reflective surface 122 of the optical collector 120 maybe protected from contamination by the debris.

FIG. 4A is a plane view for explaining an example configuration of adebris shielding assembly 370 according to an embodiment, which may beused in the light generator according to embodiments of the presentdisclosure. FIG. 4B is a cross-sectional view taken along line B-B′ inFIG. 4A. In FIGS. 4A and 4B, like reference numerals as those in FIGS. 1to 3C refer to like elements, and thus redundant descriptions thereofare omitted.

Referring to FIGS. 4A and 4B, the debris shielding assembly 370 may havea substantially same configuration as the debris shielding assembly 270Aillustrated in FIGS. 2A and 2B. Unlike the debris shielding assembly270A, the debris shielding assembly 370 may include a protective film372, and a protective frame 374 supporting the protective film 372. Theprotective frame 374 of the debris shielding assembly 370 may include asupport portion 374A, a shield portion 374B, and an outer fixing portion374C. The support portion 374A, the shield portion 374B, and the outerfixing portion 374C of the protective frame 374 may have substantiallysame configurations as those of the support portion 274A, the shieldportion 274B, and the outer fixing portion 274C of the debris shieldingassembly 270A, respectively. Unlike the debris shielding assembly 270A,the debris shielding assembly 370 may not have a through hole 272LH at acenter portion thereof. Accordingly, the laser beam (LB) passing throughthe aperture (AP) of the optical collector 120 after being radiated fromthe laser focusing system 160 illustrated in FIG. 1 may be transmittedthrough the protective film 372 to irradiate the droplet (DL) of thetarget material (see FIG. 1 ). Examples of the material of theprotective film 372 may be the same as those of protective film 172described above with reference to FIG. 1 .

Further, the support portion 374A, the shield portion 374B, and theouter fixing portion 374C of the protective frame 374, and theprotective film 372 may not have holes for the fixing member 292illustrated in FIGS. 2A and 2B. To fix the protective film 372 to theprotective frame 374, the debris shielding assembly 370 may have afixing member 394 of a press type, e.g., a clamp or a binder clip. Insome embodiments, the fixing member 392 may include a metal. However,embodiments are not limited thereto.

In the light generator 100 illustrated in FIG. 1 , the debris shieldingassembly 370 illustrated in FIGS. 4A and 4B may be employed instead ofthe debris shielding assembly 170. In the state where the opticalcollector 120 and the debris shielding assembly 370 are coupledtogether, the protective film 372 and the shield portion 374B may shieldthe protective space 180 (see FIG. 1 ) in front of the reflectivesurface 122 of the optical collector 120 from the plasma generationspace (PS)(see FIG. 1 ). Accordingly, the debris generated in the plasmageneration space (PS) is unlikely to flow into the protective space 180and the reflective surface 122 from the plasma generation space (PS), sothat the reflective surface 122 of the optical collector 120 may beprotected from contamination by the debris.

FIG. 5A is a plane view for explaining an example configuration of adebris shielding assembly 470 according to an embodiment, which may beused in the light generator according to embodiments of the presentdisclosure. FIG. 5B is a cross-sectional view taken along line B-B′ inFIG. 5A. In FIGS. 5A and 5B, like reference numerals as those in FIGS. 1to 3C refer to like elements, and thus redundant descriptions thereofare omitted.

Referring to FIGS. 5A and 5B, the debris shielding assembly 470 may havea substantially same configuration as the debris shielding assembly 270Billustrated in FIGS. 3A and 3B. Unlike the debris shielding assembly270B, the debris shielding assembly 470 may include a protective frame474 supporting the protective film 272B. The protective frame 474 of thedebris shielding assembly 470 may include a support portion 474A, ashield portion 474B, and an outer fixing portion 474C. The supportportion 474A, the shield portion 474B, and the outer fixing portion 474Cof the protective frame 474 may have substantially same configurationsas those of the support portion 274A, the shield portion 274B, and theouter fixing portion 274C of the debris shielding assembly 270B,respectively, as described above with reference to FIGS. 3A and 3B.Unlike the debris shielding assembly 270B, a central axis 470C1 of aninner diameter BD2 of the protective frame 474 and a central axis 470C2of an outer diameter AD2 of the protective frame 474 may not correspondto each other and be misaligned. The central axis 470C2 of the outerdiameter AD2 of the protective frame 474 may correspond to a centralaxis of the debris shielding assembly 470. The support portion 474A, theshield portion 474B, and the outer fixing portion 474C of the protectiveframe 474 may have widths varying in a circumferential direction withrespect to the central axis 470C2 of the outer diameter AD2 of theprotective frame 474, i.e., the central axis of the debris shieldingassembly 470. The support portion 474A may include a ring member havingan L-like cross-sectional shape extending from the shield portion 474B.

In detail, in the support portion 474A, the shield portion 474B, and theouter fixing portion 474C of the protective frame 474, a width W41 ofeach of the support portion 474A, the shield portion 474B, and the outerfixing portion 474C at a first edge of the protective frame 474 may beless than a width W42 of the same elements at a second edge of theprotective frame 474. The first and second edges of the protective frame474 may be opposite edges of the protective frame 474 along a straightline (i.e., diameter) crossing the central axis 470C2 of the outerdiameter AD2 of the protective frame 474.

In the debris shielding assembly 470, an inner diameter DD2 of thesupport portion 474A may be greater than an inner diameter BD2 of theshield portion 474B. The inner diameter DD2 of the support portion 474Amay be greater than an outer diameter OD of the edge portion of theoptical collector 120 (see FIG. 2F). An inner diameter ID of the edgeportion of the optical collector 120 may substantially be the same asthe inner diameter BD2 of the shield portion 474B.

FIG. 5C is a view illustrating a state where the optical collector 120and the debris shielding assembly 470 are coupled together.

Referring to FIGS. 5A to 5C, to couple the optical collector 120 to thedebris shielding assembly 470, the edge portion of the optical collector120 may be inserted into the support portion 474A. Once the opticalcollector 120 and the debris shielding assembly 470 are coupledtogether, the edge portion of the optical collector 120 may partially besurrounded by the support portion 474A.

In the state where the optical collector 120 and the debris shieldingassembly 470 are coupled together, the protective film 272B facing thereflective surface 122 of the optical collector 120 may extend tilted ata predetermined angle towards the optical collector 120, e.g., at thesecond acute angle β, with respect to the vertical direction (Zdirection).

The central axis 470C1 of the inner diameter BD2 of the protective frame474 and the central axis 120C of the optical collector 120 may becollinear. A straight line along the central axis 470C2 of the outerdiameter AD2 of the protective frame 474 and a straight line along thecentral axis 120C of the optical collector 120 may not be collinear(e.g., dashed lines in FIG. 5C).

When the inner diameter DD2 of the support portion 474A is greater thanthe outer diameter OD of the edge portion of the optical collector 120(see FIG. 2F), it may facilitate insertion of the edge portion of theoptical collector 120 into the support portion 474A so as to couple theoptical collector 120 to the debris shielding assembly 470. Once theedge portion of the optical collector 120 is inserted within the supportportion 474A, an upper portion of the support portion 474A and an upperportion of the shield portion 474B of the debris shielding assembly 470may partially contact the upper edge portion of the optical collector120 due to gravity, so that the upper edge portion of the opticalcollector 120 may support the debris shielding assembly 470.

In the debris shielding assembly 470, the support portion 474A of theprotective frame 474 may include a ring member extending having anL-like cross-sectional shape. In the coupling state as illustrated inFIG. 5C, as an upper edge portion of the support portion 474A having theL-like cross-sectional shape, the upper edge portion being bent towardsthe center of the protective frame 474, contacts the upper edge portionof the optical collector 120, the debris shielding assembly 470 may besupported by the optical collector 120. In the coupling positionillustrated in FIG. 5C, the edge portion of the support portion 474A,bent toward the center of the protective frame 474, may function as alatch unit that may prevent detachment of the optical collector 120downwards. That is, due to the edge portion of the protective frame 474bent towards the center of the protective frame 474, detachment of theoptical collector 120 from the protective frame 474 of the debrisshielding assembly 470 may be prevented. Accordingly, no binding toolsmay be needed for coupling the optical collector 120 to the debrisshielding assembly 470.

The shield portion 474B may have an inner surface S2 facing theprotective space 180 between the support portion 474A and the protectivefilm 272B. In the state where the optical collector 120 and the debrisshielding assembly 470 are coupled together, an edge portion of theinner surface S2 of the shield portion 474B and an edge portion of thereflective surface 122 of the optical collector 120 may contact eachother, and the inner surface S2 and the reflective surface 122 maycontinuously extend forming one plane without a step difference in acontact region between the inner surface S2 and the reflective surface122.

Although FIGS. 5A to 5C illustrate the embodiments in which the debrisshielding assembly 470 includes the protective film 272B, embodiments ofthe present disclosure are not limited thereto. For example, the debrisshielding assembly 470 may include protective film 272A as illustratedin FIGS. 2A and 2B.

In the light generator 100 illustrated in FIG. 1 , the debris shieldingassembly 470 illustrated in FIGS. 5A and 5B may be employed instead ofthe debris shielding assembly 170. In the state where the opticalcollector 120 and the debris shielding assembly 470 are coupledtogether, the protective film 272B and the shield portion 474B mayshield the protective space 180 from the plasma generation space(PS)(see FIG. 1 ). Accordingly, the debris generated in the plasmageneration space (PS) is unlikely to flow into the protective space 180through a space between protective film 272B and the optical collector120 from the plasma generation space (PS). Accordingly, the reflectivesurface 122 of the optical collector 120 may be protected fromcontamination by the debris.

FIG. 6A is a cross-sectional view for explaining an exampleconfiguration of a debris shielding assembly 570 according to anembodiment, which may be used in the light generator according toembodiments of the present disclosure. FIG. 6B is a sectional viewillustrating a state where the optical collector 120 and the debrisshielding assembly 570 are coupled together. FIG. 6C is an enlarged viewof a region “CX1” in FIG. 6B. In FIGS. 6A to 6C, like reference numeralsas those in FIGS. 1 to 3C refer to like elements, and thus redundantdescriptions thereof are omitted.

Referring to FIGS. 6A to 6C, the debris shielding assembly 570 may havea substantially same configuration as the debris shielding assembly 270Billustrated in FIGS. 3A and 3B. Unlike the debris shielding assembly270B, the debris shielding assembly 570 may include the protective film272B, and a protective frame 574 supporting the protective film 272B.The protective frame 574 of the debris shielding assembly 570 mayinclude a support portion 574A, a shield portion 574B, and an outerfixing portion 574C. The support portion 574A, the shield portion 574B,and the outer fixing portion 574C of the protective frame 574 may havesubstantially same configurations as the support portion 274A, theshield portion 274B, and the outer fixing portion 274C of the debrisshielding assembly 270B, respectively, described above with reference toFIGS. 3A and 3B. Unlike the debris shielding assembly 270B, the shieldportion 574B may have an inner surface 574EW facing the protective space180 between the support portion 574A and the protective film 272B.

In detail, the inner surface 574EW may be a curved surface. In the statewhere the optical collector 120 and the debris shielding assembly 570are coupled together, an edge portion of the inner surface 574EW of theshield portion 574B and an edge portion of the reflective surface 122 ofthe optical collector 120 may contact each other, and the inner surface574EW and the reflective surface 122 may smoothly extend forming oneplane without a step difference in a contact region between the innersurface 574EW and the reflective surface 122. In some embodiments, inthe state where the optical collector 120 and the debris shieldingassembly 570 are coupled to each other as illustrated in FIG. 6B, theinner surface 574EW of the shield portion 574B may form an ellipticsurface together with the reflective surface 122 of the opticalcollector 120. As the inner surface 574EW forms such an ellipticsurface, interruption of travel paths of EUV light (LT) reflected fromthe reflective surface 122 caused by the shield portion 574B may bereduced.

Although FIGS. 6A to 6C illustrate embodiments in which the debrisshielding assembly 570 may include the protective film 272B, embodimentsof the present disclosure are not limited thereto. For example, thedebris shielding assembly 570 may include the protective film 272A asillustrated in FIGS. 2A and 2B.

Although FIGS. 6A and 6B illustrate the embodiments that the debrisshielding assembly 570 includes the fixing member 292, embodiments ofthe present disclosure are not limited thereto. In some embodiments, thedebris shielding assembly 570 may include, instead of the fixing member292, the fixing member 394 illustrated above with reference to FIGS. 4Aand 4B. In some other embodiments, instead of including the first bufferfilm 278A, the second buffer film 278B, the outer fixing portion 574C,and the fixing member 292, the debris shielding assembly 570 illustratedin FIGS. 6A and 6B may include the protective film 272B, which may bedirectly adhered onto the shield portion 574B by pressing, or by usingthe fixing member 176 in a similar manner as described above withreference to FIG. 1 .

In the light generator 100 illustrated in FIG. 1 , the debris shieldingassembly 570 illustrated in FIGS. 6A and 6B may be employed instead ofthe debris shielding assembly 170. In the state where the opticalcollector 120 and the debris shielding assembly 570 are coupledtogether, the protective film 272B and the shield portion 574B mayshield the protective space 180 in front of the reflective surface 122of the optical collector 120 from the plasma generation space (PS)(seeFIG. 1 ). Accordingly, the debris generated in the plasma generationspace (PS) is unlikely to flow into the protective space 180 and thereflective surface 122 of the optical collector 120 from the plasmageneration space (PS), so that the reflective surface 122 of the opticalcollector 120 may be protected from contamination by the debris.

FIG. 7A is a cross-sectional view for explaining an exampleconfiguration of a debris shielding assembly 670 according to anembodiment, which may be used in the light generator according toembodiments of the present disclosure. FIG. 7B is a sectional viewillustrating a state where the optical collector 120 and the debrisshielding assembly 670 are coupled together. FIG. 7C is an enlarged viewof a region “CX2” in FIG. 7B. FIG. 7D is an enlarged partialcross-sectional view for explaining the shield portion 674B in theprotective frame 674 of the debris shielding assembly 670. In FIGS. 7Ato 7D, like reference numerals as those in FIGS. 1 to 6C refer to likeelements, and thus redundant descriptions thereof are omitted.

Referring to FIGS. 7A to 7D, the debris shielding assembly 670 may havea substantially same configuration as the debris shielding assembly 570described above with reference to FIGS. 6A to 6C. Unlike the debrisshielding assembly 570, the debris shielding assembly 670 may include aprotective frame 674 supporting the protective film 272B. A shieldportion 674B of the protective frame 674 may include a shield frame674F, and a reflective layer 674M on the shield frame 674F, thereflective layer 674M being exposed to the protective space 180.

The reflective layer 674M may have a reflective surface 674EW facing theprotective space 180 between the support portion 574A and the protectivefilm 272B. The reflective surface 674EW may be a curved surface. In someembodiments, the reflective layer 674M may include a multilayer mirror.The multilayer mirror may include a stack structure in which a pluralityof layers selected from among a Mo layer, a Si layer, a SiC layer, a B₄Clayer, a Mo₂C layer, and a Si₃N₄ layer may be alternately stacked oneanother.

In some embodiments, the reflective layer 674M may have a stackstructure as illustrated in FIG. 7D. That is, the reflective layer 674Mmay include a plurality of first reflective layers M1, a plurality ofsecond reflective layers M2, and a plurality of barrier layers BLstacked on the shield frame 674F. The first reflective layers M1 and thesecond reflective layers M2 may be alternately stacked one by one in thereflective layer 674M with one barrier layer BL between every adjacenttwo of the first reflective layer M1 and the second reflective layer M2.

In some embodiments, the first reflective layer M1 may include, e.g.,consist of, a Mo layer, and the second reflective layer M2 may include aSi layer. The barrier layer BL may include a material that may bemaintained in a stable state at a high temperature of several hundredsof degrees Celsius (° C.) or greater. In some embodiments, the barrierlayer BL may include, e.g., consist of, carbide or nitride. For example,the barrier layer BL may include a SiC layer, a B₄C layer, a Mo₂C layer,a Si₃N₄ layer, or a combination thereof. The barrier layer BL mayprevent diffusion of atoms between the first reflective layer M1 and thesecond reflective layer M2 at a high temperature. Accordingly, even whenthe reflective layer 674M reaches a high-temperature condition while thelight generator including the debris shielding assembly 670 is inoperation, performance of the reflective layer 674M may not bedeteriorated due to the barrier layer BL, and the reflective ability ofthe reflective layer 674M may be maintained.

The reflective layer 674M may further include a capping layer CP. Thecapping layer CP may include ruthenium (Ru) or silicon oxide (SiO₂). Inthe state where the optical collector 120 and the debris shieldingassembly 670 are coupled together, a top surface of the capping layer CPof the reflective layer 674M may provide the reflective surface 674EWexposed to the protective space 180.

The shield frame 674F may include a metal. For example, the shield frame674F may include Al, stainless steel, Mo, or a combination thereof.

As illustrated in FIG. 7C, the optical collector 120 may include acollector substrate 120S, and a collector reflective layer 120M on thecollector substrate 120S, the collector reflective layer 120M providingthe reflective surface 122. The collector reflective layer 120M may havea similar reflective structure to the reflective layer 674M of theshield portion 674B. The reflective layer 674M of the shield portion674B may have a thickness smaller than that of the collector reflectivelayer 120M. However, embodiments of the present disclosure are notlimited thereto. For example, the reflective layer 674M of the shieldportion 674B and the collector reflective layer 120M may have the samethickness.

In the state where the optical collector 120 and the debris shieldingassembly 670 are coupled together, an edge portion of the reflectivesurface 674EW of the shield portion 674B and an edge portion of thereflective surface 122 of the optical collector 120 may contact eachother. The reflective surface 674EW and the reflective surface 122 maysmoothly extend forming one plane without a step difference in a contactregion between the reflective surface 674EW and the reflective surface122. In some embodiments, as illustrated in FIG. 7B, in the state wherethe optical collector 120 and the debris shielding assembly 670 arecoupled together, the reflective surface 674EW of the shield portion674B may form an elliptic surface together with the reflective surface122 of the optical collector 120.

The reflective surface 674EW of the shield portion 674B may contributeto, together with the reflective surface 122 of the optical collector120, collecting and reflecting EUV light having a wavelength of about 1nm to about 31 nm, e.g., about 13.5 nm, of light having variouswavelengths radiated from the plasma. For example, the reflectivesurface 674EW of the shield portion 674B may selectively reflect EUVlight having a wavelength of about 13.5 nm. Accordingly, in addition tothe reflection efficiency of the optical collector 120, a reflectionefficiency of the reflective surface 674EW of the shield portion 674Bmay be additionally provided, so that a collecting efficiency for EUVlight may be improved in the light generator including the debrisshielding assembly 670.

Although FIGS. 7A and 7B illustrate embodiments in which the debrisshielding assembly 670 includes the protective film 272B, embodiments ofthe present disclosure are not limited thereto. For example, the debrisshielding assembly 670 may include the protective film 272A illustratedin FIGS. 2A and 2B.

Although FIGS. 7A and 7B illustrate embodiments in which the debrisshielding assembly 670 may include the fixing member 292, embodiments ofthe present disclosure are not limited thereto. In some embodiments, thedebris shielding assembly 670 may include the fixing member 394described with reference to FIGS. 4A and 4B, instead of the fixingmember 292. In some other embodiments, instead of including the firstbuffer film 278A, the second buffer film 278B, the outer fixing portion574C and the fixing member 292, the debris shielding assembly 670illustrated in FIGS. 7A and 7B may include the protective film 272B,which may be directly adhered onto the shield portion 674B by pressing,or by using the fixing member 176 in a similar manner as described abovewith reference to FIG. 1 .

In the light generator 100 illustrated in FIG. 1 , the debris shieldingassembly 670 illustrated in FIGS. 7A and 7B may be employed instead ofthe debris shielding assembly 170. In the state where the opticalcollector 120 and the debris shielding assembly 670 are coupledtogether, the protective film 272B and the shield portion 674B mayshield the protective space 180 in front of the reflective surface 122of the optical collector 120 from the plasma generation space (PS)(seeFIG. 1 ). Accordingly, the debris generated in the plasma generationspace (PS) is unlikely to flow into the protective space 180 and thereflective surface 122 of the optical collector 120 from the plasmageneration space (PS), so that the reflective surface 122 of the opticalcollector 120 may be protected from contamination by the debris.

FIG. 8 is a cross-sectional view for explaining an example configurationof a debris shielding assembly 770 according to an embodiment, which maybe used in the light generator according to embodiments of the presentdisclosure. In FIG. 8 , like reference numerals as those in FIGS. 1 to5C refer to like elements, and thus redundant descriptions thereof areomitted.

Referring to FIG. 8 , the debris shielding assembly 770 may have asubstantially same configuration as the debris shielding assembly 470illustrated in FIGS. 5A to 5C. Unlike the debris shielding assembly 470,the debris shielding assembly 770 may include the protective film 272Band a protective frame 774 supporting the protective film 272B. Theprotective frame 774 of the debris shielding assembly 770 may include asupport portion 774A, a shield portion 774B, and an outer fixing portion774C. The support portion 774A, the shield portion 774B, and the outerfixing portion 774C of the protective frame 774 may have substantiallysame configurations as the support portion 474A, the shield portion474B, and the outer fixing portion 474C of the debris shielding assembly470, respectively, as described above with reference to FIGS. 5A to 5C.Unlike the debris shielding assembly 470, the shield portion 774B mayhave an inner surface 774EW between the support portion 774A and theprotective film 272B.

In detail, the inner surface 774EW may be a curved surface. In the statewhere the debris shielding assembly 770 is coupled to the opticalcollector 120 illustrated in FIG. 5C, an edge portion of the innersurface 774EW of the shield portion 774B and an edge portion of thereflective surface 122 of the optical collector 120 may contact eachother, and the inner surface 774EW and the reflective surface 122 maysmoothly extend forming one plane without a step difference in a contactregion between the inner surface 774EW and the reflective surface 122.In some embodiments, in the state where the debris shielding assembly770 is coupled to the optical collector 120 illustrated in FIG. 5C, theinner surface 774EW of the shield portion 774B may form an ellipticsurface together with the reflective surface 122 of the opticalcollector 120.

Although FIG. 8 illustrates an embodiment in which the debris shieldingassembly 770 may include the protective film 272B, embodiments of thepresent disclosure are not limited thereto. For example, the debrisshielding assembly 770 may include the protective film 272A illustratedin FIGS. 2A and 2B.

Although FIG. 8 illustrates an embodiment in which the debris shieldingassembly 770 may include the fixing member 292, embodiments of thepresent disclosure are not limited thereto. In some embodiments, thedebris shielding assembly 770 may include the fixing member 394described above with reference to FIGS. 4A and 4B, instead of the fixingmember 292. In some other embodiments, instead of including the firstbuffer film 478A, the second buffer film 478B, the outer fixing portion774C, and the fixing member 292, the debris shielding assembly 770illustrated in FIG. 8 may include the protective film 272B, which may bedirectly adhered onto the shield portion 774B by pressing, or by usingthe fixing member in a similar manner as described above with referenceto FIG. 1 .

In the light generator 100 illustrated in FIG. 1 , the debris shieldingassembly 770 illustrated in FIG. 8 may be employed instead of the debrisshielding assembly 170. In the state where the optical collector 120 andthe debris shielding assembly 770 are coupled together, the protectivefilm 272B and the shield portion 774B may shield the protective space180 in front of the reflective surface 122 of the optical collector 120from the plasma generation space (PS)(see FIG. 1 ). Accordingly, thedebris generated in the plasma generation space (PS) is unlikely to flowinto the protective space 180 and the reflective surface 122 of theoptical collector 120 from the plasma generation space (PS), so that thereflective surface 122 of the optical collector 120 may be protectedfrom contamination by the debris.

FIG. 9 is a cross-sectional view for explaining an example configurationof a debris shielding assembly 870 according to an embodiment, which maybe used in the light generator according to embodiments of the presentdisclosure. In FIG. 9 , like reference numerals as those in FIGS. 1 to 8refer to like elements, and thus redundant descriptions thereof areomitted.

Referring to FIG. 9 , the debris shielding assembly 870 may have asubstantially same configuration as the debris shielding assembly 770described above with reference to FIG. 8 . Unlike the debris shieldingassembly 770, the debris shielding assembly 870 may include a protectiveframe 874 supporting the protective film 272B. A shield portion 874B ofthe protective frame 874 may include a shield frame 874F, and areflective layer 874M on the shield frame 874F. The reflective layer874M may have a reflective surface 874EW between the support portion774A and the protective film 272B. The reflective surface 874EW may be acurved surface. Detailed configurations of the shield frame 874F and thereflective layer 874M may be the same as those of the shield frame 674Fand the reflective layer 674M, respectively, described above withreference to FIGS. 7A to 7D.

In the state where the debris shielding assembly 870 is coupled to theoptical collector 120 illustrated in FIG. 5C, an edge portion of thereflective surface 874EW of the shield portion 874B and an edge portionof the reflective surface 122 of the optical collector 120 may contacteach other, and the reflective surface 874EW and the reflective surface122 may smoothly extend forming one plane without a step difference in acontact region between the reflective surface 874EW and the reflectivesurface 122. In some embodiments, in the stage where the debrisshielding assembly 870 is coupled to the optical collector 120illustrated in FIG. 5C, the reflective surface 874EW of the shieldportion 874B may form an elliptic surface together with the reflectivesurface 122 of the optical collector 120.

The reflective surface 874EW of the shield portion 874B may contributeto, together with the reflective surface 122 of the optical collector120, collecting and reflecting EUV light having a wavelength of about 1nm to about 31 nm, for example, about 13.5 nm, of light having variouswavelengths radiated from the plasma. For example, the reflectivesurface 874EW of the shield portion 874B may selectively reflect EUVlight having a wavelength of about 13.5 nm. Accordingly, in addition tothe reflection efficiency of the optical collector 120, a reflectionefficiency by the reflective surface 874EW of the shield portion 874Bmay be additionally provided, so that a collecting efficiency for EUVlight may be improved in the light generator including the debrisshielding assembly 870.

Although FIG. 9 illustrates an embodiment in which the debris shieldingassembly 870 may include the protective film 272B, embodiments of thepresent disclosure are not limited thereto. For example, the debrisshielding assembly 870 may include the protective film 272A illustratedin FIGS. 2A and 2B.

Although FIG. 9 illustrates an embodiment in which the debris shieldingassembly 870 may include the fixing member 292, embodiments of thepresent disclosure are not limited thereto. In some embodiments, thedebris shielding assembly 870 may include the fixing member 394described above with reference to FIGS. 4A and 4B, instead of the fixingmember 292. In some other embodiments, instead of including the firstbuffer film 478A, the second buffer film 478B, the outer fixing portion774C, and the fixing member 292, the debris shielding assembly 870illustrated in FIG. 9 may include the protective film 272B, which may bedirectly adhered onto the shield portion 874B by pressing, or by usingthe fixing member 176 in a similar manner as described above withreference to FIG. 1 .

In the light generator 100 illustrated in FIG. 1 , the debris shieldingassembly 870 illustrated in FIG. 9 may be employed instead of the debrisshielding assembly 170. In the state where the optical collector 120 andthe debris shielding assembly 870 are coupled together, the protectivefilm 272B and the shield portion 874B may shield the protective space180 in front of the reflective surface 122 of the optical collector 120from the plasma generation space (PS)(see FIG. 1 ). Accordingly, thedebris generated in the plasma generation space (PS) is unlikely to flowinto the protective space 180 and the reflective surface 122 of theoptical collector 120 from the plasma generation space (PS), so that thereflective surface 122 of the optical collector 120 may be protectedfrom contamination by the debris.

FIG. 10 is a schematic view illustrating main elements of aphotolithographic apparatus 1000 according to embodiments of the presentdisclosure.

Referring to FIG. 10 , the photolithographic apparatus 1000 may includea light generator 1100 according to embodiments of the presentdisclosure. In some embodiments, the light generator 1100 may includethe light generator 100 according to an embodiment as illustrated inFIG. 1 . In some embodiments, the light generator 1100 may include oneof the debris shielding assemblies 170, 270A, 270B, 370, 470, 570, 670,770, and 870 described above with reference to FIGS. 1 to 9 .

The photolithographic apparatus 1000 may include an illumination opticalsystem 1200, a reticle stage 1300, a blinder 1400, a projection opticalsystem 1500, and a wafer stage 1600.

The EUV light (“LT” in FIG. 10 ) generated from the light generator 1100may be radiated toward the illumination optical system 1200. The EUVlight LT may have a wavelength of about 1 nm to about 31 nm, e.g., about13.5 nm.

The illumination optical system 1200 may include a plurality of mirrors1210, 1220, 1230, and 1240. The plurality of mirrors 1210, 1220, 1230,and 1240 may focus and transmit the EUV light LT to reduce a loss of theEUV light LT. The plurality of mirrors 1210, 1220, 1230, and 1240 mayuniformly control a EUV light LT intensity distribution overall. Theplurality of mirrors 1210, 1220, 1230, and 1240 may include a concavemirror, a convex mirror, or a combination thereto to verify paths of theEUV light LT. In FIG. 10 , although the illumination optical system 1200is illustrated as including four mirrors 1210, 1220, 1230, and 1240, thenumber and locations of the mirrors in the illumination optical system1200 are not limited to the embodiment illustrated in FIG. 10 , andvarious modifications and changes may made thereto. The illuminationoptical system 1200 may include a separate vacuum chamber. Theillumination optical system 1200 may include various lenses and opticalelements not described above.

The reticle stage 1300 may move in a horizontal direction as indicatedby arrows AR1 and AR2 in FIG. 10 , with a reticle R mounted on anelectrostatic chuck therein. The reticle R may be mounted on a lowersurface of the reticle stage 1300 such that optical patterns on asurface of the reticle R face downwards. The blinder 1400 may bedisposed under the reticle stage 1300. The blinder 1400 may include aslit S. The slit S may shape the EUV light LT transmitted from theillumination optical system 1200 to the reticle R mounted on the reticlestage 1300. The EUV light LT transmitted from the illumination opticalsystem 1200 may radiate a surface of the reticle R through the slit S ofthe blinder 1400.

The EUV light (LT) reflected from the reticle R fixed to the reticlestage 1300 may be transmitted to the projection optical system 1500through the slit S. The projection optical system 1500 may receive theEUV light (LT) passed through the slit S and transmit the EUV light (LT)to a wafer W. The projection optical system 1500 may perform reductionprojection of the patterns on the reticle R onto the wafer W.

The projection optical system 1500 may include a plurality of mirrors1510, 1520, 1530, 1540, 1550, and 1560. The plurality of mirrors 1510,1520, 1530, 1540, 1550, and 1560 may correct various aberrations. InFIG. 10 , although the projection optical system 1500 is illustrated asincluding six mirrors 1510, 1520, 1530, 1540, 1550, and 1560, the numberand locations of the mirrors in the projection optical system 1500 arenot limited to the embodiment illustrated in FIG. 10 , and variousmodifications and changes may made thereto.

The wafer stage 1600 may move in a horizontal direction as indicated byarrows AR3 and AR4.

In FIG. 10 , the traveling paths of the EUV light (LT) are only forillustrative purposes, and the present disclosure of the presentapplication is not limited to the embodiment illustrated in FIG. 10 .

Although the photolithographic apparatus 1000 including the lightgenerator 1100 according to embodiments of the present disclosure aredescribed with reference to FIG. 10 , embodiments of the presentdisclosure are not limited thereto. For example, the light generator1100 according to embodiments of the present disclosure may be appliedto a test apparatus using the EUV light generated in the light generator1100. In some embodiments, the test apparatus may be an apparatus fortesting a reticle or a substrate. In some other embodiments, the testapparatus may be metrology equipment for measuring or monitoring processvariations such as focus, overlay, critical dimension, and the like.

FIG. 11 is a flowchart of a method of manufacturing an integratedcircuit (IC) device, according to embodiments of the present disclosure.

Referring to FIG. 11 , in an operation P2100, a photoresist layer may beformed on a substrate having a feature layer.

The substrate may include a semiconductor element such as silicon (Si)or germanium (Ge), or a compound semiconductor such as silicon carbide(SiC), gallium arsenide (GaAS), indium arsenide (InAs), and indiumphosphide (InP). In some embodiments, the substrate may have a siliconon insulator (SOI) structure. For example, the substrate may include aburied oxide (BOX) layer. In some embodiments, the substrate may includea conductive region, for example, a well doped with impurities or astructure doped with impurities. The substrate may have various deviceisolation structures, for example, a shallow trench isolation (STI)structure. The substrate may have a structure including at least onelayer of an insulating layer, a conductive layer, a semiconductor layer,a metal layer, a metal oxide layer, a metal nitride layer, a polymerlayer, or a combination thereof on a semiconductor wafer.

In some embodiments, the substrate may include a semiconductor wafer.The feature layer may be formed on the semiconductor wafer. In thiscase, the feature layer may be a conductive layer or an insulatinglayer. For example, the feature layer may include a metal, asemiconductor, or an insulating material. In some embodiments, thefeature layer may be a part of the substrate.

The photoresist layer may cover the feature layer. The photoresist layermay include a resist material for EUV light (13.5 nm).

Referring to FIGS. 10 and 11 , in an operation P2200, the substratehaving the photoresist layer formed thereon may be loaded on a reticlestage 1300 of the photolithographic apparatus 1000.

Referring to FIGS. 10 and 11 , in an operation P2300, the photoresistlayer may be exposed using the EUV light (LT) generated in the lightgenerator 1100 of the photolithographic apparatus 1000.

Referring to FIG. 11 , in an operation P2400, the exposed photoresistlayer may be developed to thereby form a photoresist pattern.

Referring to FIG. 11 , in operation P2500, the feature layer may beprocessed by using the photoresist pattern.

In some embodiments, to process the feature layer, the feature layer maybe etched using the photoresist pattern as an etch mask to thereby forma feature pattern. In some other embodiments, to process the featurelayer, impurity ions may be implanted into the feature layer using thephotoresist pattern as an ion implantation mask. In some otherembodiments, to process the feature layer, a separate process film maybe formed on the feature layer that is exposed through the photoresistpattern formed in operation P2400. The process film may be a conductivelayer, an insulating layer, a semiconductor layer, or a combinationthereof.

FIG. 12 is a block diagram of a memory system 3000 including anintegrated circuit (IC) device manufactured by using the method ofmanufacturing an IC device, according to embodiments of the presentdisclosure.

Referring to FIG. 12 , the memory system 3000 may include a memory card3010. The memory system 3000 may include a modem 3020 that maycommunicate via a common bus 3060, a processor 3030 such as a centralprocessing unit (CPU), random access memory 3040, and a user interface3050. These elements may transmit signals to the memory card 3010through common bus 3060 and may receive signals from the memory card3010. The memory system 3000 may include an IC device manufactured usingthe method described above with reference to FIG. 11 .

The memory system 3000 may be applicable to various electronic systems,for example, solid state disks (SSDs), CMOS image sensors (CISs),computer systems, or the like.

The IC devices disclosed herein may be encapsulated using any one of aball grid array (BGA) technique, a chip scale package (CSP) technique, aplastic leaded chip carrier (PLCC) technique, a plastic dual in-linepackage (PDIP) technique, a multi-chip package (MCP) technique, awafer-level fabricated package (WFP) technique, a wafer-level processedstack package (WSP) technique, and the like. However, embodiments of thepresent disclosure are not limited thereto.

By way of summation and review, in order to generate EUV light in thephotolithographic apparatus, laser light may be radiated onto a targetmaterial in a vacuum chamber to convert the target material into aplasma state. However, debris, e.g., particles from the target materialnot converted into plasma, may be deposited on surfaces of opticalelements in the vacuum chamber, thereby lowering operation efficiencythereof, e.g., reflectance or transmittance of the optical elements.

Attempts have been made to periodically clean the optical elements usingvarious cleaning gases or radicals from such gases. However, suchcleaning may increase the process unit price. Further, although theoptical elements may be partially cleaned by cleaning gases or radicals,repeated deposition of the debris separated from the target material maylower optical characteristics, e.g., reflectance, of the opticalelements or may deteriorate surfaces of the optical elements,consequently lowering durability of the optical elements.

In contrast, as described above with respect to one or more embodiments,a light generator according to the present disclosure may include adebris shielding assembly installed between optical elements which areprone to contamination by debris, and a plasma generation space (PS) ina chamber. Accordingly, the internal environment of the chamber may bemaintained under a stable operation condition only by periodic cleaningand/or replacement of the components of the debris shielding assembly,without cleaning the optical elements in the chamber. As such, withoutthe need to perform the cleaning process using a gas source, which mayincrease the process cost and deteriorate the optical elements,contamination of the optical elements by debris and consequentialproductivity reduction may be prevented. By inclusion of the lightgenerator according to embodiments of the present disclosure, aphotolithographic apparatus according to the present disclosure maylower the manufacturing cost and improve productivity in the process ofmanufacturing an IC device using the photolithographic apparatus.

That is, the provided light generator may prevent a reduction inoperation efficiency of optical elements exposed in an optical path andincrease the lifespan of the optical elements and may prolong apreventive maintenance (PM) cycle for cleaning and/or replacing parts ofthe optical elements. Further, the provided photolithographic apparatusmay prevent a reduction in operation efficiency of optical elementsexposed in an optical path and increase the lifespan of the opticalelements and may prolong a PM cycle for cleaning and/or replacing partsof the optical elements, thereby lowering a manufacturing cost ofintegrated circuit (IC) devices and improving productivity. Finally, theprovided method of manufacturing the IC device reduces the manufacturingcosts and improves productivity.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present invention asset forth in the following claims.

What is claimed is:
 1. A light generator, comprising: a chamber having aplasma generation space; an optical element in the chamber; and a debrisshielding assembly between the optical element and the plasma generationspace in the chamber, the debris shielding assembly including: aprotective film covering the optical element and being spaced apart fromthe optical element with a protective space therebetween, the protectivespace including an optical path, and the protective film including athrough hole in a center region of the protective film, and a protectiveframe to support the protective film and to shield the protective spacefrom the plasma generation space.
 2. The light generator as claimed inclaim 1, wherein the protective film includes a material that istransparent with respect to a laser beam having a wavelength of about1064 nm, a laser beam having a wavelength of about 10.6 μm, and extremeultraviolet (EUV) light having a wavelength of about 13.5 nm.
 3. Thelight generator as claimed in claim 1, wherein the protective filmincludes carbon nanotube, diamond, graphite, graphene, fullerene, or acombination thereof.
 4. The light generator as claimed in claim 1,wherein the protective film includes a carbon nanotube film havingsingle-wall carbon nanotubes (SWCNT), multiwall carbon nanotubes(MWCNT), or a combination thereof.
 5. The light generator as claimed inclaim 1, wherein the protective frame includes a metal.
 6. The lightgenerator as claimed in claim 1, wherein the protective frame includes:a support portion in contact with an edge portion of the opticalelement; and a shield portion integrally connected with the supportportion, the shield portion extending between the support portion andthe protective film to shield the protective space from the plasmageneration space.
 7. The light generator as claimed in claim 1, whereinthe protective frame includes: a support portion in contact with an edgeportion of the optical element; a shield portion extending between thesupport portion and the protective film to shield the protective spacefrom the plasma generation space; and an outer fixing portion facing theshield portion with the protective film therebetween, the outer fixingportion and the shield portion supporting the protective film.
 8. Thelight generator as claimed in claim 7, wherein the protective framefurther includes at least one of a first buffer film that is between theshield portion and the protective film, and a second buffer film that isbetween the protective film and the outer fixing portion.
 9. The lightgenerator as claimed in claim 7, wherein the shield portion includes anelliptic surface facing the protective space.
 10. The light generator asclaimed in claim 7, wherein the shield portion includes a reflectivesurface facing the protective space, and the reflective surface is anelliptic surface.
 11. A light generator, comprising: a chamber having aplasma generation space; an optical collector in the chamber and havinga reflective surface; and a debris shielding assembly between theoptical collector and the plasma generation space in the chamber, thedebris shielding assembly including: a protective film separated fromthe reflective surface of the optical collector with a protective spacetherebetween, the protective space including an optical path between theprotective film and the optical collector, and the protective filmfacing the reflective surface and including a through hole in a centerregion of the protective film, and a protective frame that is in contactwith an edge portion of the optical collector and supports theprotective film.
 12. The light generator as claimed in claim 11, whereinthe protective frame includes: a support portion in contact with theedge portion of the optical collector; a shield portion integrallyconnected with the support portion and having an inner surface betweenthe support portion and the protective film, the inner surface facingthe protective space; and an outer fixing portion facing the shieldportion with the protective film, the outer fixing portion and theshield portion supporting the protective film.
 13. The light generatoras claimed in claim 12, wherein the support portion includes a ringmember having a straight cross-sectional shape extending from the shieldportion.
 14. The light generator as claimed in claim 12, wherein thesupport portion includes a ring member having an L-shaped cross sectionextending from the shield portion.
 15. The light generator as claimed inclaim 12, wherein the inner surface of the shield portion defines anelliptic surface together with the reflective surface of the opticalcollector.
 16. The light generator as claimed in claim 12, wherein theshield portion includes a shield frame and a reflective layer on theshield frame, the reflective layer being exposed to the protectivespace, and the reflective layer defining an elliptic surface togetherwith the reflective surface of the optical collector.
 17. The lightgenerator as claimed in claim 11, wherein the protective frame haswidths varying in a circumferential direction with respect to a centralaxis of the debris shielding assembly.
 18. The light generator asclaimed in claim 11, wherein a central axis of an inner diameter of theprotective frame and a central axis of an outer diameter of theprotective frame are misaligned in a radial direction of the protectiveframe.